where \(\nu ^{\text{col}}_{\mathfrak {a}\mathcal {I},\mathfrak {a}^{\prime }\mathcal {I}^{\prime }}\)  is the collision frequency between particle \(\mathfrak {a}\mathcal {I}\)  and \(\mathfrak {a}^{\prime }\mathcal {I}^{\prime }\) . The momentum exchange operators are symmetric, i.e.,  \(\forall \,(\mathfrak {a}\mathcal {I}, \mathfrak {a}^{\prime }\mathcal {I}^{\prime })\in \mathcal {H}\times \mathcal {M},\;R^{\text{col}}_{\mathfrak {a}\mathcal {I}, \mathfrak {a}^{\prime }\mathcal {I}^{\prime }} = - R^{\text{col}}_{\mathfrak {a}^{\prime }\mathcal {I}^{\prime },\mathfrak {a}\mathcal {I}}\) . Note that Eq. REF  does not include the term associated with the difference in heat fluxes between species, as described by [1]} or in the 13N moment model of [2]}. The collision frequencies \(\nu ^{\text{col}}_{\mathfrak {a}\mathcal {I}, \mathfrak {a}^{\prime }\mathcal {I}^{\prime }}\)  are described in detail in [3]}. In this context, the collisional frequencies are consistent with the definition given by [2]} in the context of the 13-N moment model for multicomponent plasmas, calculated from generalized Chapman-Cowling collision integrals. The collision integrals data for \(\mathcal {M}\)  and \(\mathcal {M}_{\text{TF}}\)  have been taken from [5]} based on a review of experimental measurements. These collision integrals include charge-exchange interactions for H-H\(^+\)  and He-He\(^+\)  interactions.
